1. First, and on the whole, probably, the most common of all secondary affections, we may rank some degree of vaso-motor paralysis. It may be doubted if neuralgia ever reaches more than a very slight degree without involving more or less of this; for so-called points douloureux are themselves pretty certainly, for the most part, a phenomenon of vaso-motor palsy; and the more widely-diffused soreness, such as remains in the scalp, for instance, after attacks of pain, even at an earlier stage of trigeminal neuralgia than that in which permanently tender points are formed, is probably entirely due to a temporary skin-congestion. The phenomenon presents itself in a much more striking way in the condition of the conjunctiva seen in intense attacks of neuralgia affecting the ocular and peri-ocular branches of the fifth; one sometimes finds the whole conjunctiva deeply crimson; and, in one remarkable instance that I observed, the same shade of intense red colored the mucous membrane of the nostril of the same side. In several instances, I have seen a more than usually violent attack of sciatic pain followed by the development of a pale, rosy blush over the thinner parts of the skin of the leg, especially of the calf, which were then extremely tender, in a diffuse manner, for some time after spontaneous pain had ceased. 2. Not merely the circulation, however, but the nutrition of tissues, becomes positively affected, in a considerable number of cases. It is difficult to judge, with any exactness, in what proportion of neuralgic cases this occurs, but its slighter degrees must be very common. It has very frequently happened to me, quite accidentally, in examining with some care the fixed painful points, which are so important in diagnosis, to be struck with the decided evidence to the finger of solid thickening, evidently dependent on hypertrophic development of tissue-elements; in severe and long-standing cases, I believe this condition will always be found. Probably the change is, more usually than not, sub-inflammatory; but it is certain, on the other hand, that there are great variations in the kind of tissue-changes complicating neuralgia, and that inflammation is no necessary element in them. This subject has greatly engaged my attention, and I find myself able to give what is probably a fuller account of the matter than any yet published connectedly. The following tissues have been seen by myself to become altered under the influence of neuralgia in nerves distributed to them, or to the parts in their immediate neighborhood.